1. Field of the Invention
The present invention relates to a user authentication apparatus which uses biometrics and a user authentication method for use with the user authentication apparatus, and more particularly to a method wherein a user itself is authenticated with biometrics such as a finger print upon management of physical accessing at a gate or the like or upon management of information accessing on a terminal such as a personal computer.
2. Description of the Related Art
Conventionally, a user authentication method is used to confirm whether or not a user who manages physical accessing at a gate for entrance or the like or manages an information access right on a terminal such as a personal computer is the person itself.
In the user authentication method, authentication based on biometrics is used in addition to a method of performing authentication depending upon whether or not the user holds its possessed article such as a magnetic card or whether or not the user knows secret knowledge such as a personal identification number or a password.
Authentication based on biometrics makes use of a biological characteristic unique to each individual such as a fingerprint. A fingerprint is a pattern of the skin at a fingertip of the human being. It is known that the fingerprint has characteristics that “it is different among different people” and “it does not vary till the end of the person's life”. Even if the cuticle of a fingertip is damaged, the same fingerprint restores to the original state from the invariable corium in the interior of the cuticle. Therefore, the fingerprint is widely known as biometrics that allows accurate identification of an individual.
For example, in a user authentication process when someone requests for accessing, the person is urged to input its fingerprint. When a fingerprint is inputted, it can be used in the following manner. In particular, if the fingerprint coincides with a registered fingerprint, then the accessing is permitted, but if the fingerprint does not coincide with the registered fingerprint, then it is determined that the person is an illegal user and the accessing of the person is not permitted.
Where authentication based on a possessed article is used, an unrelated person who picked up the possessed article can use it. Also where authentication based on knowledge is used, if a person who looked furtively at or made a random guess of the knowledge inputs the knowledge, then it can acquire illegal accessing permission. In contrast, according to the method that is based on biometrics, a function that the true person itself can obtain authentication is realized.
Such a technique as described above is disclosed, for example, in Japanese Patent Laid-Open No. 33065/1992.
In the conventional user authentication method described above, where a system is employed wherein biometrics such as, for example, a fingerprint is inputted and compared with registered verification characteristics to confirm the person itself, presence of a user with whom registration or verification does not result in success when the quality of the fingerprint image is deteriorated by drying of or damage to the finger or the like cannot be ignored.
When registration or verification of a fingerprint does not result in success, typically an evading method which substitutes another authentication scheme such as, for example, inputting of a password is used. According the method, a fingerprint is inputted, and if it does not have a quality sufficient to allow automatic verification, then automatic authentication based on the fingerprint is given up and a password is inputted from a keyboard as substitute measures. However, where a password is used, an unrelated person can pose as the person itself through furtive looking or the like as described hereinabove. This makes a security hole to the entire system, which is a disadvantage of the method described above.
Naturally, it is a possible idea to additionally use, where a fingerprint is not suitable for automatic authentication, verification based on some other biometrics such as, for example, the iris. In this instance, however, an additional cost for installation and operation of an inputting apparatus for an iris image such as a camera, an illumination system for obtaining a stabilized image and so forth is required, and increase of the cost cannot be avoided.